/*
 * Asterisk -- A telephony toolkit for Linux.
 *
 * feature Proxy Channel
 * 
 * Copyright (C) 1999, Mark Spencer
 *
 * Mark Spencer <markster@linux-support.net>
 *
 * This program is free software, distributed under the terms of
 * the GNU General Public License
 */

#include <stdio.h>
#include <string.h>
#include <asterisk/lock.h>
#include <asterisk/channel.h>
#include <asterisk/channel_pvt.h>
#include <asterisk/config.h>
#include <asterisk/logger.h>
#include <asterisk/module.h>
#include <asterisk/pbx.h>
#include <asterisk/options.h>
#include <asterisk/lock.h>
#include <asterisk/sched.h>
#include <asterisk/io.h>
#include <asterisk/rtp.h>
#include <asterisk/acl.h>
#include <asterisk/callerid.h>
#include <asterisk/file.h>
#include <asterisk/cli.h>
#include <asterisk/app.h>
#include <asterisk/musiconhold.h>
#include <asterisk/manager.h>
#include <sys/socket.h>
#include <errno.h>
#include <unistd.h>
#include <stdlib.h>
#include <fcntl.h>
#include <netdb.h>
#include <arpa/inet.h>
#include <sys/signal.h>


static char *desc = "Feature Proxy Channel";
static char *type = "Feature";
static char *tdesc = "Feature Proxy Channel Driver";

static int capability = -1;

static int usecnt =0;
AST_MUTEX_DEFINE_STATIC(usecnt_lock);

#define IS_OUTBOUND(a,b) (a == b->chan ? 1 : 0)

/* Protect the interface list (of feature_pvt's) */
AST_MUTEX_DEFINE_STATIC(featurelock);

struct feature_sub {
	struct ast_channel *owner;
	int inthreeway;
	int pfd;
};

static struct feature_pvt {
	ast_mutex_t lock;				/* Channel private lock */
	char tech[AST_MAX_EXTENSION];	/* Technology to abstract */
	char dest[AST_MAX_EXTENSION];	/* Destination to abstract */
	struct ast_channel *subchan;
	struct feature_sub subs[3];		/* Subs */
	struct ast_channel *owner;			/* Current Master Channel */
	struct feature_pvt *next;				/* Next entity */
} *features = NULL;

#define SUB_REAL		0			/* Active call */
#define SUB_CALLWAIT	1			/* Call-Waiting call on hold */
#define SUB_THREEWAY	2			/* Three-way call */

static inline void init_sub(struct feature_sub *sub)
{
	sub->inthreeway = 0;
	sub->pfd = -1;
}

static inline int indexof(struct feature_pvt *p, struct ast_channel *owner, int nullok)
{
	int x;
	if (!owner) {
		ast_log(LOG_WARNING, "indexof called on NULL owner??\n");
		return -1;
	}
	for (x=0;x<3;x++) {
		if (owner == p->subs[x].owner)
			return x;
	}
	return -1;
}

static void wakeup_sub(struct feature_pvt *p, int a)
{
	struct ast_frame null = { AST_FRAME_NULL, };
	for (;;) {
		if (p->subs[a].owner) {
			if (ast_mutex_trylock(&p->subs[a].owner->lock)) {
				ast_mutex_unlock(&p->lock);
				usleep(1);
				ast_mutex_lock(&p->lock);
			} else {
				ast_queue_frame(p->subs[a].owner, &null);
				ast_mutex_unlock(&p->subs[a].owner->lock);
				break;
			}
		} else
			break;
	}
}

static void swap_subs(struct feature_pvt *p, int a, int b)
{
	int x;
	int tinthreeway;
	struct ast_channel *towner;

	ast_log(LOG_DEBUG, "Swapping %d and %d\n", a, b);

	towner = p->subs[a].owner;
	tinthreeway = p->subs[a].inthreeway;

	p->subs[a].owner = p->subs[b].owner;
	p->subs[a].inthreeway = p->subs[b].inthreeway;

	p->subs[b].owner = towner;
	p->subs[b].inthreeway = tinthreeway;

	if (p->subs[a].owner) {
		for (x=0;x<AST_MAX_FDS;x++) {
			if (a) 
				p->subs[a].owner->fds[x] = -1;
			else
				p->subs[a].owner->fds[x] = p->subchan->fds[x];
		}
	}
	if (p->subs[b].owner) {
		for (x=0;x<AST_MAX_FDS;x++)
			p->subs[b].owner->fds[x] = p->subchan->fds[x];
	}
	wakeup_sub(p, a);
	wakeup_sub(p, b);
}

static int features_answer(struct ast_channel *ast)
{
	struct feature_pvt *p = ast->pvt->pvt;
	int res = -1;
	int x;
	ast_mutex_lock(&p->lock);
	x = indexof(p, ast, 0);
	if (!x && p->subchan)
		res = ast_answer(p->subchan);
	ast_mutex_unlock(&p->lock);
	return res;
}

static struct ast_frame  *features_read(struct ast_channel *ast)
{
	static struct ast_frame null_frame = { AST_FRAME_NULL, };
	struct feature_pvt *p = ast->pvt->pvt;
	struct ast_frame *f;
	int x;
	
	f = &null_frame;
	ast_mutex_lock(&p->lock);
	x = indexof(p, ast, 0);
	if (!x && p->subchan)
		f = ast_read(p->subchan);
	ast_mutex_unlock(&p->lock);
	return f;
}

static int features_write(struct ast_channel *ast, struct ast_frame *f)
{
	struct feature_pvt *p = ast->pvt->pvt;
	int res = -1;
	int x;
	ast_mutex_lock(&p->lock);
	x = indexof(p, ast, 0);
	if (!x && p->subchan)
		res = ast_write(p->subchan, f);
	ast_mutex_unlock(&p->lock);
	return res;
}

static int features_fixup(struct ast_channel *oldchan, struct ast_channel *newchan)
{
	struct feature_pvt *p = newchan->pvt->pvt;
	int x;
	ast_mutex_lock(&p->lock);
	if (p->owner == oldchan)
		p->owner = newchan;
	for (x=0;x<3;x++) {
		if (p->subs[x].owner == oldchan)
			p->subs[x].owner = newchan;
	}
	ast_mutex_unlock(&p->lock);
	return 0;
}

static int features_indicate(struct ast_channel *ast, int condition)
{
	struct feature_pvt *p = ast->pvt->pvt;
	int res = -1;
	int x;
	/* Queue up a frame representing the indication as a control frame */
	ast_mutex_lock(&p->lock);
	x = indexof(p, ast, 0);
	if (!x && p->subchan)
		res = ast_indicate(p->subchan, condition);
	ast_mutex_unlock(&p->lock);
	return res;
}

static int features_digit(struct ast_channel *ast, char digit)
{
	struct feature_pvt *p = ast->pvt->pvt;
	int res = -1;
	int x;
	/* Queue up a frame representing the indication as a control frame */
	ast_mutex_lock(&p->lock);
	x = indexof(p, ast, 0);
	if (!x && p->subchan)
		res = ast_senddigit(p->subchan, digit);
	ast_mutex_unlock(&p->lock);
	return res;
}

static int features_call(struct ast_channel *ast, char *dest, int timeout)
{
	struct feature_pvt *p = ast->pvt->pvt;
	int res = -1;
	int x;
		
	ast_mutex_lock(&p->lock);
	x = indexof(p, ast, 0);
	if (!x && p->subchan) {
		if (p->owner->cid.cid_num)
			p->subchan->cid.cid_num = strdup(p->owner->cid.cid_num);
		else 
			p->subchan->cid.cid_num = NULL;
	
		if (p->owner->cid.cid_name)
			p->subchan->cid.cid_name = strdup(p->owner->cid.cid_name);
		else 
			p->subchan->cid.cid_name = NULL;
	
		if (p->owner->cid.cid_rdnis)
			p->subchan->cid.cid_rdnis = strdup(p->owner->cid.cid_rdnis);
		else
			p->subchan->cid.cid_rdnis = NULL;
	
		if (p->owner->cid.cid_ani)
			p->subchan->cid.cid_ani = strdup(p->owner->cid.cid_ani);
		else
			p->subchan->cid.cid_ani = NULL;
	
		strncpy(p->subchan->language, p->owner->language, sizeof(p->subchan->language) - 1);
		strncpy(p->subchan->accountcode, p->owner->accountcode, sizeof(p->subchan->accountcode) - 1);
		p->subchan->cdrflags = p->owner->cdrflags;
	} else
		ast_log(LOG_NOTICE, "Uhm yah, not quite there with the call waiting...\n");
	ast_mutex_unlock(&p->lock);
	return res;
}

static int features_hangup(struct ast_channel *ast)
{
	struct feature_pvt *p = ast->pvt->pvt;
	struct feature_pvt *cur, *prev=NULL;
	int x;

	ast_mutex_lock(&p->lock);
	x = indexof(p, ast, 0);
	if (x > -1) {
		p->subs[x].owner = NULL;
		/* XXX Re-arrange, unconference, etc XXX */
	}
	ast->pvt->pvt = NULL;
	
	
	if (!p->subs[SUB_REAL].owner && !p->subs[SUB_CALLWAIT].owner && !p->subs[SUB_THREEWAY].owner) {
		ast_mutex_unlock(&p->lock);
		/* Remove from list */
		ast_mutex_lock(&featurelock);
		cur = features;
		while(cur) {
			if (cur == p) {
				if (prev)
					prev->next = cur->next;
				else
					features = cur->next;
				break;
			}
			prev = cur;
			cur = cur->next;
		}
		ast_mutex_unlock(&featurelock);
		ast_mutex_lock(&p->lock);
		/* And destroy */
		if (p->subchan)
			ast_hangup(p->subchan);
		ast_mutex_unlock(&p->lock);
		ast_mutex_destroy(&p->lock);
		free(p);
		return 0;
	}
	ast_mutex_unlock(&p->lock);
	return 0;
}

static struct feature_pvt *features_alloc(char *data, int format)
{
	struct feature_pvt *tmp;
	char *dest=NULL;
	char *tech;
	int x;
	int status;
	struct ast_channel *chan;
	
	tech = ast_strdupa(data);
	if (tech) {
		dest = strchr(tech, '/');
		if (dest) {
			*dest = '\0';
			dest++;
		}
	}
	if (!tech || !dest) {
		ast_log(LOG_NOTICE, "Format for feature channel is Feature/Tech/Dest ('%s' not valid)!\n", 
			data);
		return NULL;
	}
	ast_mutex_lock(&featurelock);
	tmp = features;
	while(tmp) {
		if (!strcasecmp(tmp->tech, tech) && !strcmp(tmp->dest, dest))
			break;
		tmp = tmp->next;
	}
	ast_mutex_unlock(&featurelock);
	if (!tmp) {
		chan = ast_request(tech, format, dest, &status);
		if (!chan) {
			ast_log(LOG_NOTICE, "Unable to allocate subchannel '%s/%s'\n", tech, dest);
			return NULL;
		}
		tmp = malloc(sizeof(struct feature_pvt));
		if (tmp) {
			memset(tmp, 0, sizeof(struct feature_pvt));
			for (x=0;x<3;x++)
				init_sub(tmp->subs + x);
			ast_mutex_init(&tmp->lock);
			strncpy(tmp->tech, tech, sizeof(tmp->tech) - 1);
			strncpy(tmp->dest, dest, sizeof(tmp->dest) - 1);
			tmp->subchan = chan;
			ast_mutex_lock(&featurelock);
			tmp->next = features;
			features = tmp;
			ast_mutex_unlock(&featurelock);
		}
	}
	return tmp;
}

static struct ast_channel *features_new(struct feature_pvt *p, int state, int index)
{
	struct ast_channel *tmp;
	int x,y;
	if (!p->subchan) {
		ast_log(LOG_WARNING, "Called upon channel with no subchan:(\n");
		return NULL;
	}
	if (!p->subs[index].owner) {
		ast_log(LOG_WARNING, "Called to put index %d already there!\n", index);
		return NULL;
	}
	tmp = ast_channel_alloc(1);
	if (!tmp)
		return NULL;
	if (tmp) {
		for (x=1;x<4;x++) {
			snprintf(tmp->name, sizeof(tmp->name), "Feature/%s/%s-%d", p->tech, p->dest, x);
			for (y=0;y<3;y++) {
				if (p->subs[x].owner && !strcasecmp(p->subs[x].owner->name, tmp->name))
					break;
			}
			if (y < 3)
				break;
		}
		tmp->type = type;
		ast_setstate(tmp, state);
		tmp->writeformat = p->subchan->writeformat;;
		tmp->pvt->rawwriteformat = p->subchan->pvt->rawwriteformat;
		tmp->readformat = p->subchan->readformat;
		tmp->pvt->rawreadformat = p->subchan->pvt->rawreadformat;
		tmp->pvt->pvt = p;
		tmp->pvt->send_digit = features_digit;
		tmp->pvt->call = features_call;
		tmp->pvt->hangup = features_hangup;
		tmp->pvt->answer = features_answer;
		tmp->pvt->read = features_read;
		tmp->pvt->write = features_write;
		tmp->pvt->exception = features_read;
		tmp->pvt->indicate = features_indicate;
		tmp->pvt->fixup = features_fixup;
		p->subs[index].owner = tmp;
		ast_mutex_lock(&usecnt_lock);
		usecnt++;
		ast_mutex_unlock(&usecnt_lock);
		ast_update_use_count();
	} else
		ast_log(LOG_WARNING, "Unable to allocate channel structure\n");
	return tmp;
}


static struct ast_channel *features_request(const char *type, int format, void *data, int *cause)
{
	struct feature_pvt *p;
	struct ast_channel *chan = NULL;
	p = features_alloc(data, format);
	if (!p->subs[SUB_REAL].owner)
		chan = features_new(p, AST_STATE_DOWN, SUB_REAL);
	return chan;
}

static int features_show(int fd, int argc, char **argv)
{
	struct feature_pvt *p;

	if (argc != 3)
		return RESULT_SHOWUSAGE;
	ast_mutex_lock(&featurelock);
	p = features;
	while(p) {
		ast_mutex_lock(&p->lock);
		ast_cli(fd, "%s -- %s/%s\n", p->owner ? p->owner->name : "<unowned>", p->tech, p->dest);
		ast_mutex_unlock(&p->lock);
		p = p->next;
	}
	if (!features)
		ast_cli(fd, "No feature channels in use\n");
	ast_mutex_unlock(&featurelock);
	return RESULT_SUCCESS;
}

static char show_features_usage[] = 
"Usage: feature show channels\n"
"       Provides summary information on feature channels.\n";

static struct ast_cli_entry cli_show_features = {
	{ "feature", "show", "channels", NULL }, features_show, 
	"Show status of feature channels", show_features_usage, NULL };

int load_module()
{
	/* Make sure we can register our sip channel type */
	if (ast_channel_register(type, tdesc, capability, features_request)) {
		ast_log(LOG_ERROR, "Unable to register channel class %s\n", type);
		return -1;
	}
	ast_cli_register(&cli_show_features);
	return 0;
}

int reload()
{
	return 0;
}

int unload_module()
{
	struct feature_pvt *p;
	/* First, take us out of the channel loop */
	ast_cli_unregister(&cli_show_features);
	ast_channel_unregister(type);
	if (!ast_mutex_lock(&featurelock)) {
		/* Hangup all interfaces if they have an owner */
		p = features;
		while(p) {
			if (p->owner)
				ast_softhangup(p->owner, AST_SOFTHANGUP_APPUNLOAD);
			p = p->next;
		}
		features = NULL;
		ast_mutex_unlock(&featurelock);
	} else {
		ast_log(LOG_WARNING, "Unable to lock the monitor\n");
		return -1;
	}		
	return 0;
}

int usecount()
{
	int res;
	ast_mutex_lock(&usecnt_lock);
	res = usecnt;
	ast_mutex_unlock(&usecnt_lock);
	return res;
}

char *key()
{
	return ASTERISK_GPL_KEY;
}

char *description()
{
	return desc;
}